Recently, a system for integratively operating various electric instruments mounted on an automotive vehicle is realized. Specifically, the system operates the instruments such as a navigation device, an air-conditioner and an audio unit in such a manner that information for operating of the instruments is shown on a display, and a passenger in the vehicle operates a button shown on the display performed by, for example, touch panel operation or remote control operation.
However, according to the above system, it is necessary for the passenger to watch the display when the passenger operates the button. Accordingly, when a driver in the vehicle operates the button, a problem arises that it is difficult for the driver to recognize where the button is disposed and what happens to the instrument after the button is operated.
In view of the above problem, a technique disclosed in Japanese Patent Application Publication No. 2001-84875 is well known to solve the problem. This technique relates to a device called a haptic device for controlling a reaction force in accordance with a position of the button and a state of the instrument. Further, the haptic device applies not only the reaction force but also external assist force to an operation direction.
More specifically, when a volume of a radio or a CD player is operated, an operator feels a friction of a manual operation device when the manual operation device is operated to turn up the volume. Further, the operator feels an acceleration of the manual operation device when the manual operation device is operated to turn down the volume. Thus, the external force is applied to the manual operation device. As a result, even when the volume is turned up, it can be avoided that a sound to be outputted to a compartment of the vehicle is rapidly increased. Further, when the operator wants to turn down the volume, the volume can be rapidly reduced. Thus, a problem such as interception of conversation and audio listener is resolved. Further, the above control details are different in each instrument as an object of operation by the manual operation device (e.g., the navigation device, the air conditioner and the audio unit). Furthermore, the manual operation device can switch the object instrument.
However, in the above technique, a problem arises when a user removes the instrument mounted on the vehicle (e.g., a portable navigation device) from the vehicle. For example, when the operator switches the operation object instrument by using the manual operation device, the operation object instrument to be switched does not exist in the vehicle practically. In this case, even when the operator operates the manual operation device to switch to the object operation instrument, nothing happens. Thus, the operator may feel uncomfortable.
Further, when a user changes a regularly used vehicle to another vehicle, the user may feel uncomfortable since a friction force of the manual operation device in the other vehicle is different from that in the regularly used vehicle.
Further, another user drives the vehicle and the other user may change adjustment of the friction force in accordance with his preference just before the user drives the same vehicle. In this case, the user may feel uncomfortable.